In recent years, a display mounted with an organic EL panel has been proposed in association with widespread use of a thin display. The organic EL panel is liable to cause problems such as ambient light reflection and background reflection because the panel includes a metal layer having high reflectivity. In view of the foregoing, it has been known that those problems are prevented by providing a circularly polarizing plate on a viewer side. A product obtained by laminating a retardation film typified by a cycloolefin (COP)-based resin film (typically a λ/4 plate) so that its slow axis may form an angle of about 45° with respect to an absorption axis of a polarizer has been known as a general circularly polarizing plate. The retardation film made of a COP-based resin is known to have the so-called flat wavelength dispersion characteristic. That is, its retardation value is independent of a wavelength of measuring light and substantially constant. When a circularly polarizing plate including a retardation film having such flat wavelength dispersion characteristic is used in the organic EL panel, a problem in that an excellent reflection hue is not obtained arises.
To solve such problem as described above, a circularly polarizing plate including a retardation film having the so-called reverse wavelength dispersion dependency (reverse wavelength dispersion characteristic) has been proposed (for example, Patent Literature 1). That is, the retardation value of the film increases depending on the wavelength of measuring light. When such circularly polarizing plate is used in the organic EL panel, ambient light reflection in a front direction can be significantly alleviated, and a reflection hue in the direction can be significantly improved. However, when the panel is viewed from an oblique direction, a hue different from the hue in the front direction is obtained and the hue difference has been a serious problem. A problem in that display characteristics of the panel change over time has also been confirmed.